The invention relates to fluid analytical devices, and in particular to fluid analytical devices providing multi-step analysis and detection functions.
Generally, when blood detection is performed, blood cells and plasma must be separated from whole blood, thereafter detection can be performed on the plasma. Conventionally, plasma is separated from whole blood by centrifugal force using a centrifugal rotor with specific channels.
U.S. Pat. No. 5,061,381 discloses a centrifugal rotor capable of separating cellular components and plasma from whole blood. As shown in FIG. 1, the centrifugal rotor 10 comprises a top layer 12, a middle layer 14, and a bottom layer 16. The top layer 12, middle layer 14, and bottom layer 16 respectively provide different channels. Whole blood can be input to the centrifugal rotor 10 via a blood application port 22. The cellular components and plasma can be separated from the whole blood by rotation of the centrifugal rotor 10 and interaction of the top layer 12, middle layer 14, and bottom layer 16. Specifically, as having different specific weights, the cellular components and plasma move radially and are separated by centrifugal force generated during rotation of the centrifugal rotor 10.
Nevertheless, the aforementioned centrifugal rotor 10 has the following drawbacks. As shown in FIG. 2, the simultaneously and radially moving cellular components and plasma separate at radial passages 94. The cellular components are stopped by the narrow radial passages 94 and remain at a peripheral wall 91 of a collection chamber 90, while the plasma continues to flow into test wells 92 via the radial passages 94. Although most cellular components are stopped by the narrow radial passages 94 and cannot flow into the test wells 92 during operation of the centrifugal rotor 10, some cellular components may, however, be pushed into the radial passages 94 by centrifugal force. At this point, the cellular components (blood cells) are subject to compression of the radial passages 94 and shear force. The cellular components (blood cells) are thus broken and flow into the test wells 92, contaminating the plasma therein and adversely affecting subsequent analysis of the plasma.
Moreover, to prevent overflow of whole blood during rotation of the centrifugal rotor 10, an overflow chamber 44 is disposed in the middle layer 14 to collect the overflowing whole blood.
In its entirety, as shown in FIG. 1 and FIG. 2, the structure (or channel structure) of the centrifugal rotor 10 is complex, and potentially inconvenient to manufacture or operate.
Hence, there is a need for a fluid analytical device providing a simplified structure and easy operation. The fluid analytical device can provide the functions of multi-step fluid analysis and detection.